Have Enemies Randomly Shoot#

Having enemies randomly shoot is easier than periodically shooting enemies as shown in Have Enemies Periodically Shoot. This is because we don’t have to track how long it has been since we last fired.

See the highlighted lines for what is specific to this example.

Screenshot of using sprites to shoot things
sprite_bullets_random.py#
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"""
Show how to have enemies shoot bullets at random intervals.

If Python and Arcade are installed, this example can be run from the command line with:
python -m arcade.examples.sprite_bullets_random
"""
import arcade
import random

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600
SCREEN_TITLE = "Sprites and Random Bullets Example"


class MyGame(arcade.Window):
    """ Main application class """

    def __init__(self, width, height, title):
        super().__init__(width, height, title)

        arcade.set_background_color(arcade.color.BLACK)

        self.frame_count = 0
        self.player_list = None
        self.enemy_list = None
        self.bullet_list = None

        self.player = None

    def setup(self):
        """ Setup the variables for the game. """
        self.player_list = arcade.SpriteList()
        self.enemy_list = arcade.SpriteList()
        self.bullet_list = arcade.SpriteList()

        # Add player ship
        self.player = arcade.Sprite(":resources:images/space_shooter/playerShip1_orange.png", 0.5)
        self.player_list.append(self.player)

        # Add top-left enemy ship
        enemy = arcade.Sprite(":resources:images/space_shooter/playerShip1_green.png", 0.5)
        enemy.center_x = 120
        enemy.center_y = SCREEN_HEIGHT - enemy.height
        enemy.angle = 180
        self.enemy_list.append(enemy)

        # Add top-right enemy ship
        enemy = arcade.Sprite(":resources:images/space_shooter/playerShip1_green.png", 0.5)
        enemy.center_x = SCREEN_WIDTH - 120
        enemy.center_y = SCREEN_HEIGHT - enemy.height
        enemy.angle = 180
        self.enemy_list.append(enemy)

    def on_draw(self):
        """Render the screen. """

        self.clear()

        self.enemy_list.draw()
        self.bullet_list.draw()
        self.player_list.draw()

    def on_update(self, delta_time):
        """All the logic to move, and the game logic goes here. """

        # Loop through each enemy that we have
        for enemy in self.enemy_list:

            # Have a random 1 in 200 change of shooting each 1/60th of a second
            odds = 200

            # Adjust odds based on delta-time
            adj_odds = int(odds * (1 / 60) / delta_time)

            if random.randrange(adj_odds) == 0:
                bullet = arcade.Sprite(":resources:images/space_shooter/laserBlue01.png")
                bullet.center_x = enemy.center_x
                bullet.angle = -90
                bullet.top = enemy.bottom
                bullet.change_y = -2
                self.bullet_list.append(bullet)

        # Get rid of the bullet when it flies off-screen
        for bullet in self.bullet_list:
            if bullet.top < 0:
                bullet.remove_from_sprite_lists()

        self.bullet_list.update()

    def on_mouse_motion(self, x, y, delta_x, delta_y):
        """ Called whenever the mouse moves. """
        self.player.center_x = x
        self.player.center_y = 20


def main():
    """ Main function """
    window = MyGame(SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_TITLE)
    window.setup()
    arcade.run()


if __name__ == "__main__":
    main()